1. Field of the Invention
This invention relates to protective sleeves for fluorescent lamp tubes, and more particularly concerns a safety sleeve apparatus which includes a safety sleeve encapsulating a fluorescent tube for protecting the tube from physical damage and end caps for preventing the tube from sliding out of the sleeve and breaking if the sleeve is tilted from the horizontal during installation of the tube into a pair of sockets in a lamp fixture.
This invention also relates to creating an air space around the tube to protect it from cold and increase the lumen production of fluorescent tube apparatus.
2. Description of the Prior Art
Fluorescent tubes have been provided with protective safety sleeves before, but there is a danger when installing a sleeve-protected fluorescent tube which is eight feet long, for example, that it may fall out of the sleeve when it is tilted from the horizontal while attempting to insert the tube into the sockets of the fluorescent tube receptacle. Also, it has been a problem to protect the environment from broken tube components if the tube breaks as in a refrigerated food cabinet or in a pharmaceutical hopper.
Previous fluorescent tubes with protective shields have included a sleeve with two press fit end caps, a sleeve with caps held onto the sleeve with adhesive, and a sleeve that is shrink-wrapped around the tube. In the press fit end cap assemblies, during installation the fluorescent tube could push out an end cap from the sleeve and slip out of the sleeve resulting in the fluorescent tube falling and breaking.
The tubes held in with caps affixed in the sleeve by an adhesive have the problem of not being reusable if a protective sleeve or a tube should break.
Also, the shrink-wrapped sleeve does not provide an airspace around the tube that would act as a heat insulation shield in cold environments.
Another problem is presented when fluorescent tubes are used in refrigerated or in freezer applications, as in refrigerated food cabinets, or in public garages in the winter time when the weather is cold. A fluorescent tube is designed to produce its rated lumen output when the wall temperature at the mid-point of the tube reaches 100° F. If you put a fluorescent tube into a freezer environment, the light output of the tube is severely compromised.
To summarize, the prior art safety sleeves for fluorescent lamp tubes include:
1. A sleeve with two end caps that are press fitted into the ends of the sleeve, which has the problem of the fluorescent lamp tube, due to its weight, pushing an end cap off of the end of the sleeve and the fluorescent tube sliding out of the sleeve and breaking if the sleeve is tilted from horizontal during installation of the tube into a light socket.
2. A sleeve with end caps that are held in by adhesives, which has the drawback of not being able to use the sleeve more than once, since after the fluorescent tube is spent, the sleeve is discarded with the fluorescent tube.
3. A shrinkable sleeve that is shrink-wrapped onto the fluorescent tube, which is discarded with the tube when the lamp is spent, and which does not provide an airspace between the sleeve and the fluorescent tube.
The lighting industry has moved away from fluorescent lighting in parking garages and many outdoor areas in parts of the country where they get cold weather. Many have gone to high intensity discharge fixtures because the lumen output in cold weather is better, but the system cost is high. Another disadvantage is that if power is interrupted, it takes time for the lamp/ballast to cool down to allow it to re-strike the lamp. On the other hand, fluorescent tubes are just turned off and on and do not have this problem. Also, fluorescent tubes are less expensive and consume lower wattage.